General Characteristics of Protista
- They are mostly unicellular but some are multicellular and colonial organisms.
- They are either free-living or parasitic.
- They have aerobic mode of respiration and have mitochondria for cellular respiration.
- They are true eukaryotes and are nucleated.
- They have (9+2) arrangement of flagella and have membranous organelles.
- They reproduce both sexually (syngamy) and asexually.
- They are grouped into 3 categories: animal like (protozoa), fungus like, and plant-like.
- According to the categories, they have different modes of nutrition, like heterotrophy or autotropohy.
- Plant-like protists (algae) have chlorophyll and accessory pigments, named xanthophylls, phycobilins, and carotene.
Plant Like Characteristics: e.g. Algae
They are further classified as Euglenoids, Diatoms, and Dinoflagellates.
Euglenoids Characteristics - e.g. Euglena
- They are unicellular
- Animal like movement
- Flagellum present
- Presence of nucleus, chloroplasts, flagellum, and cell membrane
- Asexual reproduction
- Two part shell of silicon glass
- Golden brown in color
- Stores food in form of oil
- They are di-flagellated
- Phosphorescent algae
- Covered with plates
- Color renders 'red tides'
- Has toxins
- Presence of pseudopodia
- Shell composed of calcium
- They are heterotrophs
- Free living, saprophytic, mutualistic or parasitic
- Sarcodina: amoeba like movement (pseudopodia)
- Flagellates: moves with flagella
- Paramecium: moves with cilia
- Sporozoans: produce spores
- They are multicellular
- Change forms during life cycle
- Tend to live in damp climate
- Plasmodial (acellular), slime molds (Myxomycetes)
- Kingdoms: Chromista, Archaezoa, Protista/Protozoa
- Candidate Kingdoms: Archaezoa, Euglenozoa, Alveolata, Stramenopila, Rhodophyta
The cell wall of red algae is made up of agar and carageenan. Both are used as additives in food. Agar is used as a gelling agent and thickener. Shells made up of calcium carbonate, protects them from grazing animals. In brown algae, cell wall of algin and cellulose protects them against waves and exposure to air. This component ensures uniform freezing and melting of food items. Fungi have cell wall made up of cellulose or chitin.
I hope the information provided about protists has proven useful to you. You can view their images and check out different forms over the Internet to expand your knowledge a little more.